[vsnet-grb-info 17054] GRB 150922A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18358
SUBJECT: GRB 150922A: Fermi GBM observation
DATE:    15/09/23 09:04:05 GMT
FROM:    Oliver Roberts at UCD/Fermi  <oliver.roberts at ucd.ie>

O.J. Roberts (UCD), A. von Kienlin (MPE) and
C. Meegan (UAH),report on behalf of the Fermi GBM Team:

"At 05:37:29.08 UT on 22 September 2015, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 150922A (trigger 464593053 / 150922234), which was
also detected by IPN (Svinkin et al. 2015, GCN 18357).
The GBM on-ground location is consistent with the IPN
position. The angle from the Fermi LAT boresight is
about 38 degrees.

The GBM light curve shows a short burst with a
duration (T90) of 0.144 s (50-300 keV). The time-averaged
spectrum from T0-0.016 to T0+0.128 s is best fit by a
power law function with an exponential high-energy cutoff.
The power law index is -0.55 +/- 0.11 and the cutoff energy,
parameterized as Epeak, is 625 +/- 97  keV.

The event fluence (10-1000 keV) in this time interval
is (8.0 +/- 0.4) E-07 erg/cm^2. The 64 ms peak photon
flux measured starting from T0-0.016 s in the 10-1000 keV
band is 23.0 +/- 1.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."